Conyers, who's been in Congress since 1965 and was a founding member of the Congressional Black Caucus, said the 6-2 ruling adds to a series of high court decisions that are "hostile towards our history of civil rights and our struggle for equality."

The court reversed a 2013 appeals court decision that found Michigan's 2006 ban against factoring race into public university admissions unconstitutional.

"Michigan voters exercised their privilege to enact laws as a basic exercise of their democratic power," Justice Anthony Kennedy wrote in the majority opinion. "... the courts may not disempower the voters from choosing which path to follow."

The constitutional amendment was approved in 2006 by 58 percent of Michigan voters.

African Americans at the time made up about 7 percent of the University of Michigan undergraduate student population in Ann Arbor. That number has that's since declined to 4.6.

“Our nation has come a long way in seeking to end discrimination, but our work is far from complete at a time of continued under representation of minorities in higher education and many walks of life," said Conyers in a statement.

"One has to look no farther for evidence of this than the fact that there was a significant drop in minority enrollment after Proposal 2 was enacted. African-American enrollment declined by one third at the University of Michigan Ann Arbor between 2006 and 2012, at the same time overall enrollment expanded by one tenth. Now is not the time for the Court to blindly ignore the biases that continue to exist in our society.”

Michigan Attorney General Bill Schuette, who defended the ban against the court challenge raised by Detroit group By Any Means Necessary, called the ruling a monumental victory.

"The ruling is a victory for the Constitution, a victory for Michigan citizens, and a victory for the rule of law," he said. “In 2006, the citizens of Michigan enshrined the basic concept of equality and fairness into our Constitution. It is fundamentally wrong to treat people differently based on the color of their skin."

Conyers, by contrast, viewed the ruling is counter to constitutional equal protection.

"It is unfortunate that this Court allowed Proposal 2 to overrun the intent of the Constitution’s equal protection clause: protecting disadvantaged minorities from discrimination,” he said.

“The blatant unfairness of this approach was highlighted by the Sixth Circuit in their opinion striking down Proposal 2 stating that, while ‘sons and daughters of alumni’ and children of big donors are afforded those non-merit considerations in the admissions process, Proposal 2 would require a minority student to ‘convince the Michigan electorate to amend its constitution - an extraordinary expensive process and the most arduous of all the possible channels for change.'"

Detroit attorney Shanta Driver, who argued against the ban on behalf of the plaintiffs, called the ruling "a racist decision."

"It is this Court’s Plessy v. Ferguson," she said in a statement, referring to the 1896 ruling that upheld state laws mandating racial segregation. "The decision of the Court today makes clear that this Court intends to do nothing to defend the right to equality in politics, opportunity, rights, hopes and aspirations of its Latina/o, black, Native American and other minority citizens...

"Any university that claims to use a holistic admissions policy cannot turn a blind eye to the effects of institutional racism and inequality in K-12 education, and must consider the real-life experiences and obstacles that its minority applicants face."